RIGHT ON 1 UNIT 5 library - attend

CHARACTERISTICS OF LIFE The world is filled with familiar objects, such as tables, rocks, plants, pets, and automobiles. Which of these objects are living or were once living? What are the criteria for assigning something to the living world or the nonliving world? Biologists have established that living things share seven characteristics of life. These characteristics are organization and the presence of one or more cells, response to a stimulus (plural, stimuli), homeostasis, metabolism, growth and development, reproduction, and change through time. Organization and Cells Organization is the high degree of order within an organism’s internal and external parts and in its interactions with the living world. For example, compare an owl to a rock. The rock has a spe- cific shape, but that shape is usually irregular. Furthermore, differ- ent rocks, even rocks of the same type, are likely to have different shapes and sizes. In contrast, the owl is an amazingly organized individual, as shown in Figure 1-2. Owls of the same species have the same body parts arranged in nearly the same way and interact with the environment in the same way. Copyright © by Holt, Rinehart and Winston. All rights reserved. ORGANISM (Barn Owl) ORGAN (Owl’s Ear) TISSUE (Nervous Tissue Within the Ear) CELL (Nerve Cell) Every living organism has a level of organization. The different levels of organization for a complex multicellular organism, such as an owl, are shown in the figure below. FIGURE 1-2 THE SCIENCE OF LIFE 7 All living organisms, whether made up of one cell or many cells, have some degree of organization. A cell is the smallest unit that can perform all life’s processes. Some organisms, such as bacteria, are made up of one cell and are called unicellular (YOON-uh-SEL-yoo-luhr) organisms. Other organisms, such as humans or trees, are made up of multiple cells and are called multicellular (MUHL-ti-SEL-yoo-luhr) organisms. Complex multicellular organisms have the level of orga- nization shown in Figure 1-2. In the highest level, the organism is made up of organ systems, or groups of specialized parts that carry out a certain function in the organism. For example, an owl’s ner- vous system is made up of a brain, sense organs, nerve cells, and other parts that sense and respond to the owl’s surroundings. Organ systems are made up of organs. Organs are structures that carry out specialized jobs within an organ system. An owl’s ear is an organ that allows the owl to hear. All organs are made up of tissues. Tissues are groups of cells that have similar abilities and that allow the organ to function. For example, nervous tissue in the ear allows the ear to detect sound. Tissues are made up of cells. A cell must be covered by a membrane, contain all genetic information necessary for replication, and be able to carry out all cell functions. Within each cell are organelles. Organelles are tiny structures that carry out functions necessary for the cell to stay alive. Organelles contain biological molecules, the chemical compounds that provide physical structure and that bring about movement, energy use, and other cellular functions. All biological molecules are made up of atoms. Atoms are the simplest particle of an ele- ment that retains all the properties of a certain element. Response to Stimuli Another characteristic of life is that an organism can respond to a stimulus—a physical or chemical change in the internal or external environment. For example, an owl dilates its pupils to keep the level of light entering the eye constant. Organisms must be able to respond and react to changes in their environment to stay alive. ORGANELLE (Mitochondrion) BIOLOGICAL MOLECULE (Phospholipid) ATOM (Oxygen) cell from the Latin, cella meaning “small room,” or “hut” Word Roots and Origins www.scilinks.org Topic: Characteristics of Life Keyword: HM60257 mb06se_bios01.qxd 5/18/07 10:37 AM Page 7 8 CHAPTER 1 Homeostasis All living things, from single cells to entire organisms, have mecha- nisms that allow them to maintain stable internal conditions. Without these mechanisms, organisms can die. For example, a cell’s water content is closely controlled by the taking in or releas- ing of water. A cell that takes in too much water will rupture and die. A cell that doesn’t get enough water will also shrivel and die. Homeostasis (HOH-mee-OH-STAY-sis) is the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Organisms have regulatory systems that maintain internal conditions, such as temperature, water content, and uptake of nutrients by the cell. In fact, multi- cellular organisms usually have more than one way of maintain- ing important aspects of their internal environment. For example, an owl’s temperature is maintained at about 40°C (104°F). To keep a constant temperature, an owl’s cells burn fuel to produce body heat. In addition, an owl’s feathers can fluff up in cold weather. In this way, they trap an insulating layer of air next to the bird’s body to maintain its body temperature. Metabolism Living organisms use energy to power all the life processes, such as repair, movement, and growth. This energy use depends on metabolism (muh-TAB-uh-LIZ-uhm). Metabolism is the sum of all the chemical reactions that take in and transform energy and materials from the environment. For example, plants, algae, and some bacteria use the sun’s energy to generate sugar molecules during a process called photosynthesis. Some organisms depend on obtaining food energy from other organisms. For instance, an owl’s metabolism allows the owl to extract and modify the chemi- cals trapped in its nightly prey and use them as energy to fuel activities and growth. Growth and Development All living things grow and increase in size. Some nonliving things, such as crystals or icicles, grow by accumulating more of the same material of which they are made. In contrast, the growth of living things results from the division and enlargement of cells. Cell division is the formation of two new cells from an existing cell, as shown in Figure 1-3. In unicellular organisms, the primary change that occurs following cell division is cell enlargement. In multi- cellular life, however, organisms mature through cell division, cell enlargement, and development. Development is the process by which an organism becomes a mature adult. Development involves cell division and cell differen- tiation, or specialization. As a result of development, an adult organism is composed of many cells specialized for different func- tions, such as carrying oxygen in the blood or hearing. In fact, the human body is composed of trillions of specialized cells, all of which originated from a single cell, the fertilized egg. This unicellular organism, Escherichia coli, inhabits the human intestines. E. coli reproduces by means of cell division, during which the original cell splits into two identical offspring cells. FIGURE 1-3 Observing Homeostasis Materials 500 mL beakers (3), wax pen, tap water, thermometer, ice, hot water, goldfish, small dip net, watch or clock with a second hand Procedure 1. Use a wax pen to label three 500 mL beakers as follows: 27°C (80°F), 20°C (68°F), 10°C (50°F). Put 250 mL of tap water in each beaker. Use hot water or ice to adjust the tem- perature of the water in each beaker to match the temperature on the label. 2. Put the goldfish in the beaker of 27°C water. Record the number of times the gills move in 1 minute. 3. Move the goldfish to the beaker of 20°C water. Repeat observations. Move the goldfish to the beaker of 10°C. Repeat observations. Analysis What happens to the rate at which gills move when the temp- erature changes? Why? How do gills help fish maintain homeostasis? Quick Lab mb06se_bios01.qxd 5/18/07 10:37 AM Page 8 THE SCIENCE OF LIFE 9 Reproduction All organisms produce new organisms like themselves in a process called reproduction. Reproduction, unlike other characteristics, is not essential to the survival of an individual organism. However, because no organism lives forever, reproduction is essential for the continuation of a species. Glass frogs, as shown in Figure 1-4, lay many eggs in their lifetime. However, only a few of the frogs’ off- spring reach adulthood and successfully reproduce. During reproduction, organisms transmit hereditary informa- tion to their offspring. Hereditary information is encoded in a large molecule called deoxyribonucleic acid, or DNA. A short segment of DNA that contains the instructions for a single trait of an organism is called a gene. DNA is like a large library. It contains all the books—genes—that the cell will ever need for making all the struc- tures and chemicals necessary for life. Hereditary information is transferred to offspring during two kinds of reproduction. In sexual reproduction, hereditary information recombines from two organisms of the same species. The resulting offspring are similar but not identical to their parents. For example, a male frog’s sperm can fertilize a female’s egg and form a single fer- tilized egg cell. The fertilized egg then develops into a new frog. In asexual reproduction, hereditary information from different organisms is not combined; thus the original organism and the new organism are genetically the same. A bacterium, for example, reproduces asexually when it splits into two identical cells. Change Through Time Although individual organisms experience many changes during their lifetime, their basic genetic characteristics do not change. However, populations of living organisms evolve or change through time. The ability of populations of organisms to change over time is important for survival in a changing world. This factor is also impor- tant in explaining the diversity of life-forms we see on Earth today.

Žodžių apklausa unit 5 Right on 1

Health 11/12 Review for Final Exam Core Concepts - Mental and Emotional Health, Substance Abuse Prevention, Safety and Violence Prevention, Family Life and Human Sexuality, Disease Prevention and Control, Healthy Eating Health Education Skills - goal setting, decision making, accessing information/resources, analyzing influences, communication, self-management, advocacy DIMENSIONS of Wellness - social, spiritual, emotional/mental, environmental, financial, intellectual, multicultural, occupational, physical, sexual RISK factors - anything that increases the risk of disease, injury, or illness. PROTECTIVE factors - anything that decreases the risk of disease, injury, or illness. INTERNAL health factors - health factors that can be either hereditary and genetic or acquired elements -- include smoking and personal diet or eating habits. Example – a genetic predisposition to an illness. EXTERNAL health factors - health factors that are part of the direct outer environment, the geographical location, micro-organisms, socio-economic elements that could affect an individual's health. Example – being unable to afford mental health services. Unit 1- Managing Personal and Community Wellness Explain Maslow’s Hierarchy of Needs in your own words using the image provided. Explain how each Social Determinant of Health may impact a person’s health. Levels of Disease Prevention • PRIMARY The goal is to avoid conditions altogether. • SECONDARY The goal is early detection. • TERTIARY The goal is to minimize the damage (manage). Define the following terms. Fads/Trends Sleep hygiene Driver safety Unit 2- Investigating Social Ecological Factors on Well-Being Socio-Ecological Model – The SEM examines how health behaviors form based on characteristics of individuals, communities, nations and levels in between. Each level overlaps with other levels signifying how the best public health strategies are those that encompass and target a wide range of perspectives. Interpersonal (personal) health vs. intrapersonal (relationship) health Health INEQUITY - systemic, ingrained and unjust barriers that prevent segments of the population from having the opportunity of health leading to health disparity. IMPLICIT BIAS - a form of bias that occurs automatically and unintentionally, that nevertheless affects judgments, decisions, and behaviors. Research has shown implicit bias can contribute to unequal access to quality healthcare, negative patient-provider relationships and interactions; and create mistrust in the healthcare system and practitioners among patients. This can contribute to health disparities. Health DISPARITY - represents a difference in health between populations. It is often used to describe disease burden and other negative health outcomes socially disadvantaged groups may face. Health EQUITY - The opposite of health inequity. It describes a system that supports a high standard of health and healthcare for all people. Racism - Beliefs, attitudes, institutional arrangements, and acts that tend to denigrate individuals or groups because of phenotypic characteristics or ethnic group affiliation. DISCRIMINATION - An unjust differential treatment of a person or a group. PRIVILEGE- The unearned access to resources and social power that are only available to some because of their membership within certain social groups. OPPRESSION is the act of taking away choices from others and can be defined as a system that maintains advantage and disadvantage based on social identities and that acts on multiple levels from interpersonal to institutional and societal. (internalized, interpersonal, institutional, structural) Systematic Oppression - Intentional disadvantage of groups of people based on their identity while advantaging members of dominant group (race, gender, sexual orientation, language, size, ability, etc.). Intersectionality - The complex, cumulative way in which the effects of multiple forms of discrimination (such as racism, sexism, and classism) combine, overlap, or intersect especially in the experiences of marginalized individuals or groups Unit 3- Accessing Resources and Communicating to Support Mental and Emotional Health What is anger? What is anxiety? What is stress? STRESSORS are the things that cause stress. Stressors can be internal and external. A stressor may be a one-time or short-term occurrence, or it can happen repeatedly over a long time. INTERNAL Stressors - are made by your belief system and the way you evaluate yourself. Examples include pessimistic attitude, negative self-talk, deep need to be perfect, low self-esteem or body image, unhealthy standards for self. EXTERNAL Stressors - are stressful things that happen in your surroundings and/or in your environment. Examples include busy schedules, work problems, family issues, financial trouble, social problems, injury, unforeseen circumstances. Socio-economic issues are also a part of external stressors such as poverty, violence, and racism. Define the following mental health conditions. Depression Eating disorders NSSI Non-suicidal self-injury Grief/Loss Suicide prevention A.C.T. • ACKNOWLEDGE- Tell them in a caring way that you recognize that they are having a problem • CARE- You can show you care by actively listening - put away anything else you are doing, make eye contact, sit down, ask questions. • TELL-(call 988 for additional help and support) - Tell them it is important that they speak with a trusted adult. Help them figure out who this may be and offer to go with your friend. A social norm is an unwritten, informal rule meant to guide behavior among the of society. It distinguishes between acceptable and unacceptable, good and bad, and so on. Social norms can influence a person with emotional or mental health disorders, access to care and stigmatize their situation. STIGMA- a mark of disgrace associated with a particular circumstance, quality, or person. • Self-stigma - This describes the internalized stigma that people with mental health conditions feel about themselves. • Public stigma - This refers to the negative attitudes around mental health from people in society. • Institutional stigma - This is a type of systemic stigma that arises from corporations, governments, and other institutions. Unit 4- Evaluating Risks of Substance Use and Abuse Harm Reduction - a set of practical strategies and ideas aimed at reducing negative consequences associated with drug use. Explain how each level of the Social Ecological Model is impacted by addiction. Individual Relationship Community Society SEM Level Contributing/Risk Factors to substance use Preventative/Protective Factors for substance use Individual Interpersonal/Relationship Community Society Unit 5- Analyzing Influences to Examine Ways to Increase Safety and Reduce Violence HATE CRIME - a crime, usually violent, motivated by prejudice or intolerance toward an individual’s national origin, ethnicity, color, religion, gender, gender identity, sexual orientation, or disability. Explain how the media influences violence in society. The Pyramid of Hate Explain the escalation of hate using the Pyramid of Hate visual. List several hate crime motivators. Example: age HEALTHY Relationship Signs - comfortable pace, trust, honesty, independence, respect, equality, kindness, taking responsibility, healthy conflict, fun UNHEALTHY Relationship Signs - intensity, possessiveness, manipulation, isolation, sabotage, belittling, guilting, volatility, deflecting responsibility, betrayal Sexual Assault is a sexual behavior WITHOUT consent. Human trafficking - the recruitment, harboring, transportation, provision, or obtaining of a person for labor or services, using force, fraud, or coercion for the purpose of subjection to involuntary servitude, peonage, debt bondage, or slavery. Sex trafficking - commercial sex act induced by force, fraud, or coercion, or in which the person induced to perform such an act has not attained 18 years of age. Trafficking happens using… • Force - using violence to control someone. • Fraud - using lies to control someone. • Coercion - using threats to control someone. Unit 6- Family Life and Human Sexuality Agency - A belief about yourself and the extent to which you can act on that belief. • The ability to choose freely one’s own narrative. • To embrace the idea that I am the cause (or agent) of my own thoughts and actions. • Personal agency is a personal responsibility for who we are, what we experience, what we do about that experience, and how we shape our world to give us more of the experiences we want. SEXUAL Agency • The ability to choose your own interests and desires vs. what we see in the media or others’ perceptions • The ability to identify, communicate, and negotiate one’s sexual needs • The ability to initiate behaviors that allow for the satisfaction of those needs Sexually Explicit Material - photographs, videos, films, magazines, and books whose primary themes, topics, or depictions involve sexuality that may cause sexual arousal. Sexual scripts - thoughts, patterns, or behavior that a person has about themselves in a romantic or sexual context. It is how people picture themselves or want to project themselves in front of others. Reproductive Rights of Teens - In Maryland, teens have the right to an abortion, keep their child, obtain and use birth control, paternity tests, adoption, give up custody of their child within 10 days of birth (Safe Haven Law). • REPRODUCTIVE RIGHTS- legal rights and the freedom of the individual to control decisions regarding contraception, abortion, sterilization and childbirth. • SAFE HAVEN LAW- a distressed parent who is unable or unwilling to care for their infant can safely give up custody of their baby, no questions asked. CONSENT is an agreement between participants to engage in sexual activity. • It is clearly and freely communicated, verbal, and affirmative. Consent CANNOT be given if… • A person is underage, one or both partners is intoxicated or incapacitated by drugs or alcohol, one partner is asleep or unconscious, one partner feels pressured, threatened or intimidated, or one partner holds a position of power or authority over the other. Unit 7- Advocating for Enhanced Nutrition, Food Systems, and Health Outcomes Dietary Guidelines for Americans Guideline 1: Follow a Healthy Dietary Pattern at Every Life Stage Guideline 2: Customize and Enjoy Food and Beverage Choices to Reflect Personal Preferences, Cultural Traditions, and Budgetary Considerations Guideline 3: Focus on Meeting Food Group Needs with Nutrient-Dense Foods and Beverages, and Stay Within Calorie Limits Guideline 4: Limit Foods and Beverages Higher in Added Sugars, Saturated Fat, and Sodium, and Limit Alcoholic Beverages FOOD DESERT- a neighborhood where there is little or limited access to healthy and affordable food such as fruits, vegetables, whole grains, low-fat milk and other foods that make up the full range of a healthy diet. FOOD INSEQURITY lack of access to a sufficient amount of food because of limited funds. More than 49 million American households are considered food insecure and are vulnerable to poor health as a result. PROCCESED FOODS- any raw agricultural commodities that have been washed, cleaned, milled, cut, chopped, heated, pasteurized, blanched, cooked, canned, frozen, dried, dehydrated, mixed or packaged — anything done to them that alters their natural state.

Create me a multiple choice test questions with 4 options on the following topic:Consumer Education for Different Audience 1. Children and Youth: - Focus: Building foundational knowledge about basic consumer concepts, making safe choices, understanding money and value, and recognizing scams and unsafe situations. 2. Teens and Young Adults: - Focus: Building financial literacy, responsible debt management, understanding contracts and agreements, responsible technology use, online safety, and consumer rights. 3. Working Adults and Families: - Focus: Managing budgets, making informed purchasing decisions, understanding credit and debt, finding consumer protection resources, and navigating complex financial products (mortgages, insurance, investments). 4. Seniors: - Focus: Protecting themselves from scams and fraud, understanding common consumer issues like telemarketing, identity theft, and online scams, managing medications and healthcare costs, and accessing community resources. 5. Special Populations: - Focus: Adapting consumer education programs to the specific needs of people with disabilities, immigrants, refugees, and other marginalized communities. 6. Business and Industry:- Focus: Understanding ethical marketing practices, complying with consumer protection laws, and providing clear and accurate information to consumers. 7. Policymakers and Regulators: - Focus: Understanding consumer needs, developing effective consumer protection laws, enforcing regulations, and ensuring a fair and competitive marketplace. Adapting consumer education programs for children, teens, and seniors requires tailoring content and delivery methods to their unique needs and learning styles. Children (Ages 5-12): - Understanding the concept of money: Teaching children about saving, spending, and the value of money. - Developing basic budgeting skills: Helping children learn to make choices about how to spend their allowance or pocket money. EFFECTIVE STRATEGIES •Focus on basic concepts: Introduce core concepts like saving, spending, and budgeting in a fun and engaging way. Use simple language and relatable examples. •Real-life scenarios: Use age-appropriate scenarios to illustrate financial concepts, like buying toys or snacks. •Parental involvement: Encourage parent participation and provide resources to help them reinforce lessons at home. Teens (Ages 13-18): - Building budgeting and financial planning skills: Teaching teens how to manage their money, set financial goals, and plan for the future. - Navigating the digital marketplace: Equipping teens with the knowledge and skills to make safe and informed online purchases, understand digital marketing, and protect themselves from scams. EFFECTIVE STRATEGIES • Practical skills: Focus on skills relevant to teens, like managing money for social activities, saving for college, and understanding credit cards. • Digital literacy: Address the growing influence of online shopping, social media advertising, and financial scams. • Real-world applications: Connect financial concepts to real-life decisions teens make, like choosing a part-time job or making purchases online. Seniors (Ages 65+) - Managing retirement savings and healthcare costs: Providing information and resources on retirement planning, Medicare and Medicaid, and other healthcare options. - Navigating the digital world: Offering technology training and resources to help seniors access online services and information safely and securely. EFFECTIVE STRATEGIES • Addressing specific concerns: Focus on topics relevant to senior citizens, like retirement planning, managing healthcare expenses, and avoiding scams. • Clear and concise communication: Use simple language and visual aids to ensure easy understanding. • Social interaction: Create opportunities for seniors to share experiences and learn from each other. Teaching Financial Literacy in school and Communities In Schools: Curriculum Integration: Financial literacy concepts can be seamlessly integrated into existing subjects, making learning more relevant and engaging. - Math: Budgeting exercises, calculating interest rates, analyzing financial data, and understanding compound interest are all natural applications of math skills. - Social Studies: Exploring the history of money, financial institutions, economic systems, and the impact of financial decisions on society provide valuable context. - Economics: Discussions about supply and demand, inflation, investment, and the role of consumers in the economy enhance financial literacy. Dedicated Courses: Offering elective courses or workshops specifically focused on personal finance provides deeper dives into crucial topics. - Personal Finance: Cover budgeting, saving, investing, credit, debt management, and insurance. - Entrepreneurship: Introduce concepts like business planning, marketing, financial forecasting, and managing cash flow. In Communities: Community Centers and Libraries: Workshops, seminars, and classes tailored to adults and families provide accessible learning opportunities. - Financial Planning: Cover budgeting, retirement planning, debt management, and estate planning. - Homeownership: Provide guidance on buying, selling, and maintaining a home. - Consumer Protection: Educate individuals about their rights and how to avoid scams. Partnerships with Financial Institutions: Collaborations with banks, credit unions, and financial advisors offer valuable resources, workshops, and financial literacy programs. Consumer Education for Low-Income and Vulnerable Populations Low-income refers to individuals or households with limited financial resources, typically below a certain threshold. Low-income individuals may face challenges like: 1. Limited education and job opportunities 2. Poor living conditions and housing 3. Food insecurity and malnutrition Causes of low income: 1. Unemployment or underemployment 2. Low-paying jobs or minimum wage 3. Limited education or skills 4. Single parenthood or large family size Vulnerable population'' is a term that is used to describe a group of people who possess some sort of disadvantage. elderly people, people with low incomes, homeless people, people in prison, migrant workers, pregnant women, Family Consumer Education: Managing Household Finances and Resources Financial literacy is the ability to understand and manage personal finances effectively. 1. Debt Debt is money you spend that isn’t yours. If you borrow money from the bank, use a credit card, or take out a short-term loan, or a payday loan, you are accumulating debt. Good debt is considered money borrowed for things that are absolutely necessary for making a life e.g. a house and for advancing your money-making potential e.g. an education. Bad debt is considered borrowing money or using a credit card to pay for things you don’t need, such as expensive clothes, hi-tech electronics, eating out at restaurants, going on holidays, etc. 2. Saving Saving is an essential part of financial wellness, a secure present, and a happy future. 3. Budgeting Budgeting is the life skill of planning and managing your money. By understanding exactly where your money goes every month, you are empowered to create an actionable plan by which you can spend less, by curtailing those unnecessary expenses and saving more for the things you need and want. 4. Investing Investing is all about creating and growing the wealth you need to enjoy a financially secure and happy future. It’s about putting your money into something that will make you a profit over time, such as property, retirement funds, and unit trusts Integrating Consumer Education into the Home Economics Curriculum. Integrating consumer education into the home economics curriculum can provide students with essential skills for making informed choices about their personal finances, food, clothing, and overall well-being. Here are some strategies and ideas for effectively incorporating consumer education: Financial Literacy Budgeting: Teach students how to create and manage a personal budget, including setting financial goals, tracking expenses, and understanding savings. Saving and Investment: Cover the basics of saving, including different saving accounts, and introduce concepts related to investing. Food and Nutrition Food Label Literacy: Engage students in learning how to read and interpret food labels, including nutrition facts and ingredient lists. Grocery Shopping Skills: Teach students how to compare product costs, understand unit pricing, and make healthy, budget-friendly choices while shopping. Clothing and Textile Education Consumer Choices in Clothing:Discuss factors influencing clothing purchases, such as quality, price, and sustainability. Fashion and Trends: Analyze the impact of marketing and advertising on consumer behavior regarding clothing. Sustainable Purchasing Eco-Friendly Choices: Raise awareness about environmentally friendly products and the importance of sustainability in consumer choices. Project-Based Learning - Assign real-life projects where students must apply their knowledge, such as creating a meal plan within a budget, planning a shopping list based on nutrient needs, or evaluating the cost-effectiveness of different products. Technology Integration - Use technology to teach students about online shopping, price comparison websites, and apps that aid budgeting and financial planning. Collaborative Learning Opportunities - Organize team projects where students work together to solve consumer-related problems, emphasizing teamwork and communication skills. Assessment and Reflection - Incorporate assessments that allow students to reflect on what they have learned about consumer education and how they can apply these skills in their daily lives.

All living things are made up of one or more cells. A cell is the smallest unit that can carry on all of the processes of life. Beginning in the 17th century, curious naturalists were able to use microscopes to study objects too small to be seen with the unaided eye. Their studies led them to propose the cellular basis of life. Hooke In 1665, English scientist Robert Hooke studied nature by using an early light microscope, such as the one in Figure 4-1a. A light micro- scope is an instrument that uses optical lenses to magnify objects by bending light rays. Hooke looked at a thin slice of cork from the bark of a cork oak tree. “I could exceedingly plainly perceive it to be all perforated and porous,” Hooke wrote. He described “a great many little boxes” that reminded him of the cubicles or “cells” where monks live. When Hooke focused his microscope on the cells of tree stems, roots, and ferns, he found that each had similar little boxes. The drawings that Hooke made of the cells he saw are shown in Figure 4-1b. The “little boxes” that Hooke observed were the remains of dead plant cells, such as the cork cells shown in Figure 4-1c. SECTION 1 OBJECTIVES ● Name the scientists who first observed living and nonliving cells. ● Summarize the research that led to the development of the cell theory. ● State the three principles of the cell theory. ● Explain why the cell is considered to be the basic unit of life. VOCABULARY cell cell theory Robert Hooke used an early microscope (a) to see cells in thin slices of cork. His drawings of what he saw (b) indicate that he had clearly observed the remains of cork cells (300) (c). FIGURE 4-1 (a) (b) (c) Copyright © by Holt, Rinehart and Winston. All rights reserved. 70 CHAPTER 4 Leeuwenhoek The first person to observe living cells was a Dutch trader named Anton van Leeuwenhoek. Leeuwenhoek made microscopes that were simple and tiny, but he ground lenses so precisely that the magnification was 10 times that of Hooke’s instruments. In 1673, Leeuwenhoek, shown in Figure 4-2a, was able to observe a previ- ously unseen world of microorganisms. He observed cells with green stripes from an alga of the genus Spirogyra, as shown in Figure 4-2b, and bell-shaped cells on stalks of a protist of the genus Vorticella, as shown in Figure 4-2c. Leeuwenhoek called these organisms animalcules. We now call them protists. THE CELL THEORY Although Hooke and Leeuwenhoek were the first to report observ- ing cells, the importance of this observation was not realized until about 150 years later. At this time, biologists began to organize information about cells into a unified understanding. In 1838, the German botanist Matthias Schleiden concluded that all plants were composed of cells. The next year, the German zoologist Theodor Schwann concluded the same thing for animals. And finally, in his study of human diseases, the German physician Rudolf Virchow (1821–1902) noted that all cells come from other cells. These three observations were combined to form a basic theory about the cel- lular nature of life. The cell theory has three essential parts, which are summarized in Table 4-1. Anton van Leeuwenhoek (1632–1723) is shown here with one of his hand-held lenses (a). Leeuwenhoek observed an alga of the genus Spirogyra (b) and a protist of the genus Vorticella (c). FIGURE 4-2 TABLE 4-1 The Cell Theory All living organisms are composed of one or more cells. Cells are the basic units of structure and function in an organism. Cells come only from the reproduction of existing cells. (a) (b) (c) www.scilinks.org Topic: Cell Theory Keyword: HM60241 mb06se_csfs01.qxd 5/18/07 10:54 AM Page 70

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